The growth cycle of lung cancer varies in time due to the different types of lung cancer pathology, and there is usually not an exact time. It is a relatively long process from the early malignant transformation of cells to form cancer cells, and then the growth to form lung cancer lesions, which usually takes about several years. The growth doubling time of cancer cells varies from one lung cancer cell to another, generally 80 days for small cell lung cancer, 223 days for adenocarcinoma cells, and about 104 days for squamous carcinoma. Lung cancer is usually asymptomatic at the initial stage, but as the disease spreads to the middle and late stages, it can cause symptoms in several systems of the body, such as cough, chest pain, abdominal pain, headache, weight loss, etc. Therefore, it is recommended to have regular medical checkups every year to detect lung cancer as early as possible.